Metered Dose Inhalers: The HFA Propellant

The metered dose inhaler (MDI) was developed in the 1950 s. The propellant used in MDIs until recently contained CFCs (Chlorofluorocarbons). You may find when you replace your MDI that a different propellant is used in the inhaler. This is an HFA (hydrofluoroalkane) propellant.